The expression and distribution of
integrin subunits alpha 2 and alpha 3 and two of their putative
ligands,
type IV collagen and
laminin, were examined by immunohistochemistry in specimens from 33 consecutive patients operated on for colorectal
adenocarcinomas. Both tumour cells and normal epithelium expressed the alpha 2 and alpha 3 subunits. Two typical patterns of expression could be discerned; a basolateral expression and a diffuse cytoplasmic expression. The stained tumour specimens were assessed according to (i) distribution of
integrin expression (diffusely cytoplasmic or basolateral), (ii) continuity in basolateral
integrin expression, and (iii) interconnection of
integrin expression and expression of
type IV collagen and
laminin. These parameters were then related to tumour differentiation, tumour stage according to Dukes' classification,
DNA-ploidy and patient survival (median observation time was 30 months; range 24-35). The continuity in the basolateral expression of alpha 3 but not of alpha 2, correlated with the basal membrane expression of
type IV collagen (P < 0.001). Loss of continuity in the basolateral expression of both
integrins was significantly related to impaired tumour differentiation (alpha 2 P = 0.02; alpha 3 P = 0.01), more advanced Dukes' stage (alpha 2 = 0.07, alpha 3 P < 0.001), survival rate (both
integrins P < 0.05), but not to
DNA-ploidy. These data suggest that determination of the pattern of expression of the
integrin subunits alpha 2 and alpha 3 in the preoperative biopsy and the surgical specimen could be used as a prognostic
indicator.